Hydraulic vise



E. T. OLSON HYDRAULIC VISE Nov. 9, 1954 3 Sheets-Sheet 1 Filed July 20,1953 INVENTOR hmw 7. 0mm

BY (ML-M r S p I ATTORNEYJ Nov. 9, 1954 I Filed July 20, 1955 E. T.OLSON 2,693,727 HY'DRAULIC VISE 3 Sheeis-Sheet 2 E. T. OLSON HYDRAULICVISE Nov. 9, 1954 3 Sheets-Sheet 5 Filed July 20, 1953 a: m T m 5 8. w d5 1 M a I 2 mo. 0 W.

2. s a a S. /7 2. o 3 n w an l E. x a m hw a g x 3 BY Quid 44% ATTORNEY;

United States Patent HYDRAULIC VISE Elmer T. Olson, Minneapolis,.Minn.,assignor of 'onehalf to William J. Rawitzer, Minneapolis, Minn.

Application July 20, 1953, Serial No. 368,928

7 Claims. (Cl. 81-17.2)

My invention relates to improvements in vises such as used by variousartisans for holding their work and which tool, of'course, comprisesessentially a pair of jaws which may be moved apart to receive the workand then forced together to obtain a firm, vise-like grip upon the work.i

In a large majority of cases the vise jaws are operated by means of ahand screw but for modern production work, where time is extremelyimportant, the manual manipulation of the vise screw is slow andimpractical. For such usage hydraulic or air operated vises of varioustypes have been devised so that the operator may close the visehydraulically. Obviously such hydraulic actuation saves time and whererelatively powerful gripping forces are necessary they are available bysupplying fluid under the necessary pressure. All of such hydraulicvises, however, to my knowledge have numerous disadvantages chief amongwhich is their relatively large size by comparison with the vise whichthey control and the very considerable expense involved by comparisonwith the more ordinary types of vises. In many instances size of theoperating hydraulic element is particularly important for clearancereasons and also a number of such hydraulic vises have required footmanipulation by the operator in order to develop the pressure used, sothat the saving in time actually is negligible and considerable eflortis still required upon the part of the operator.

In accordance with the primary object of my invention I provide for thehydraulic actuation of the vise an extremely simple and compact fluidactuated device which may be readily associated with the vise, whetherin the initial manufacture thereof or in the replacement field forconversion of present manually operated vises. As another object of myinvention I provide hydraulic actuating means for a vise whichinterferes in no way with the normal hand screw operation of the jawsbut which at the will of the operator provides for instant hydraulicactuation to close the movable jaw toward the stationary jaw through apredetermined distance suflicient to grip the work powerfully andtightly. This hydraulic adjustment of the vise jaws may be takenadvantage of in any manually adjusted spacing between the jaws and it isthus necessary for the operator only to make a rough adjustment by thehand screw, following which he may handle large numbers of work piecesin an absolute minimum of time. A further object of my invention is toprovide the hydraulic actuation of a vise using as the prime source offluid pressure the ordinary shop supply of compressed air with which allshops of any size are provided. In order then to develop the relativelymuch greater fluid pressures necessary for proper work gripping at thevise jaws I provide an operating cylinder having a large piston moved bythe air pressure and a small piston which drives fluid intothe actuatingcylinder upon the vise itself, thus magnifying the. pressure effectivefor the movement of the vise jaw. By thus increasing the effectivepressure usable at the vice I am able to use an actuating cylinder ofrelatively small diameter so that it becomes unnecessary to build up thevise in order to accommodate the large diameter cylinders so oftennecessary with present day hydraulic and air operated vises. In fact, I-find that I am able to provide a vise with more than adequate grippingpower in which the operating cylinder is actually smaller than the vise"ice body itself so that there is no overhead space problem at all.

These and other more detailed and specific objects will be disclosed inthe course of the following specifica tion, reference being had to theaccompanying drawings, in WhlCh- Fig. 1 is a side elevation of a commontype of bench vise as provided with they hydraulic actuating mechanismof my invention, the vise jaws being shown as gripping a work piece.

Fig. 2 is an enlarged vertical and longitudinal section through the viseand the associated hydraulic actuating cylinder assembly. In this casethe vise jaws are shown preliminary to the operation thereof by thehydraulic assembly.

Fig. 3 is a similar sectional view through the rear portion of the viseshowing the position assumed by the parts when fluid pressure is appliedfor closing the vise jaws on the work piece.

Fig. 4 is a somewhat enlarged diametrical vertical section taken on theirregular line 4-4 in Fig. 2.

Fig. 5 is a vertical longitudinal sectional view showing means for thehydraulic operation of machine vises such as used for holding work upondrill presses, milling machines and the like.

Fig. 6 is a similar view showing a modification of the hydraulicactuating means for the machine type of vise.

Referring now more particularly and by reference characters to thedrawing, the vise as shown in Figs. 1 through 4 is of the common benchtype universally used by machinists and other workers for various benchwork and the same conventionally includes a vise body 10 having a base11 by which it is firmly secured to the bench 12. Ordinarily there is aswivel connection between the base and the vise body, but the same isomitted for simplicity in the present disclosure. Formed upon the upperfrontal portion of the body 10 is the stationary vise jaw 13 andtherebelow the body has a forwardly and rearwardly extending bore 14 inwhich the correspondingly shaped and sized shank 15 of a movable visejaw 16 is slidably mounted. As usual the jaws 1316 are provided withremovable face blocks 17 and 18 respectively. The distance between thejaws 13 and 16 is ordinarily adjusted by means of a hand screw 19 havinga handle 20 at its forward end for convenient manipulation. The screw 19is journaled rearwardly through an axial bore 21 in the shank 15 and therear portion is provided with threads 22 having engagement withcorresponding internal threads 23 on the interior of an elongatedtubular vise nut 24. For straight hand operation the nut 24, which isslidably mounted into the rear end of the bore 21, is secured in somefashion to the vise 10 so that the opposite rotation of the screw 19will of necessity move the jaw 16 forwardly and rearwardly and therebyadjust the jaw with respect to the stationary jaw 13.

In order to operate the jaw 16 and its shank 15 there is a fitting 25about the screw 19 where it emerges at the front of the vise whichprevents relative axial movement of the movable jaw and the hand screwin the usual manner.

According to my invention I provide fluid actuated or hydraulic meansfor positioning the entire hand screw and nut assembly forwardly andrearwardly with respect to the vise body 10 so that in any adjustedposition of these parts, and therefore in any adjusted spacing of thevise jaws 13-16, I am able to urge the movable jaw toward the stationaryjaw by the action of fluid under pressure. When not thus in use suchhydraulic actuating means serves to hold the nut 24 against forward orrearward movement so that the vise may bemanually adjusted as aforesaid.Fundamentally this hydraulic actuating assembly takes the form of arelatively movable piston and cylinder, one of which elements isattached to the vise nut 24 and the other of which is attached tocylinder, the latter being fundamentally that disclosed in my priorcopending application Serial- No. 325,406, filed- December 11, 1952, andoperating what is therein referred to as a fluid actuated clamp.

For the accommodation of fluid operation in the standard form ofmanually operated bench vise as, depicted; in the drawing, the vise nut24' is. provided, at its rear end with a. tapped socket or opening 26into which the diametrically reduced forward; end 27 of an anchor stud28 is screwed. Preferably, although not necessarily, the protruding,rearward portion of the anchor stud 28 is enclosed, by a. sleeve 29;which. is, held. in place by a nut 30 screwed upon; the threaded rearend 31- of the stud. The nut 30 also holds in place upon this assemblyan actuating cylinder 32 the rear. nd 33 of Which is provided with, a.central bore 34 fitting the external diameter of sleeve 29; The wall ofthe cylinder 32 is considerably larger in diameter, than the sleeve 29so that space is'provided forwardly of the end 33 to slidably receive animmovably-mounted piston 35,. the external diameter of which is machinedto fit, into the cylinder. The P t n 5 is a so y nd i al; as a. rear end3.6: again provided with a bore 37; to .nic ely and slidably fitthesleeve 2 9. Thusthere are provided opposed annular end facesorsurfaces.3& upon the respective ends of the cylinder andpistonagainstwhich fluid pressure may be applied; for moving one ofsaidelements with respect to the other, axially along the sleeve 29.Fluid tight seals are provided by conventional inner and outer 0- rings,designated at 39. The internal diameter of the cylindrical wall or skirtof the piston is made slightly larger than the exposed rear end 40 ofthe vise nut 24 against which the s1eeve29-is pulled up tight by theanchor stud 28.

Also forming part of the assembly is an end extension sleeve 41 whichreplaces the ordinary end cap and plug assembly (not shown) of thevisehere chosen for illustration, and which sleeve 41 has adiametrically reduced forward end 42 to slip into the bore 14 of thevise body 19 where these parts are secured together by a tangentialcross pin 43. Thesleeve 41 is bored out, as indicated at 44, to clearthe vise-nut 24 but the interior of the sleeve is provided with alongitudinal keyway 45 in which there slides a key 46 on the vise nut topermit the necessary forward and=rearward movement of said nut whileholding-the nut against rotation. The sleeve 41 extends rearwardly.from. the vise body 10 and has a.

rear end. face 4.7-adjacent which there normally rests the forward endface 48 of the skirt of the cylinder 32. The rear endof the sleeve iscounterbored at 49 to receive the forward endjportiontof the skirt ofthe piston 35 which pistonis secured to the sleeve, and thereby to thevise body 10, by means of a lock screw or pin 50, as clearly seen inFigs. Z and 3. Conversion to hydraulic operation of vises presently,in.use requires replacement only of the vise nutandend plug.

Fluidunder pressure is supplied to the rear end of the cylinder 32through a laterally opening, tapped socket 51 fromwhich thereis aforwardly opening bore 52. A conventional fitting 53 screwed in thesocket is then connectedby a flexible line, 54. to the fluid pressuresource. Preferably I. employ the. ordinary compressed air supply of theshop for, the development of sufficient fluid pressure in the cylinderv32 to develop the relatively considerable thrustwh-ich is necessarytoobtain a powerful grip upon the work in the vise jaws. For this purpose,as seen in Fig. l, a line 55 from the compressed air supply isconnectedthrough a manually controlled valve 56 to the end of a dualoperating cylinder, designated generally at 57. Conveniently thiscylinder 57 may be suspended below the bench12 and the valve 56 carriedby a bracket or control panel 58a convenient to the hand of theoperator, but the specific location of these parts is, of course,immaterial. In any event, the operating cylinder 57'has a large diametercylinder section 58 communicating with a coaxial and considerablysmaller cylinder section 59. A large piston 60 provided with an O-ringseal 61 is slidable in the cylinder section 58 and from its center thereis extended a plunger 62 which slides in the smaller cylinder section 59and which has O-ring seals 63. A fitting 64 conducts the compressed airfrom the valve 56 into the end of the large cylinder section 58 so thatits pressure is brought to bear upon the large piston 60. An expansioncoil spring 65 coiled around the plunger 62 acts as a return spring forthe piston assembly. The extremity of-the small cylinder section 59 isclosed by an end plug 66 in which there is a fitting 67' connected tothe aforesaid line 54; This-line 54 and the communicating parts of theactuating cylinder 32 and of the cylinder section 59 are all filled withhydraulic fluid and thus as air pressure is brought to bear upon thepiston 60 the resulting travel of the plunger 62 will move the body offluid. through the line 54 and into the space between the end surfaces38 of the cylinder 32 and piston 35 at the vise- Because of thedifference in diameters of the piston 60 and plunger 62 the resultingfluid pressure brought to bear upon these end sur-- faces 38 is, builtup to a point at which relatively tremcndous thrust may be developedeven though the cylinder 32 is, as shown, actually smaller physicallythan is the vise body 10. Thus I am enabled to employ the relatively lowpressures of the shop air supply for the eflicient operation of the visewithout requiring that the vise actuating cylinder be so large indiameter as to bring on clearance problemsv as would otherwise be thecase.

In operation, assuming that; the vise has been adjusted roughly byoperation of the hand: screw 19, asit isshown: in Fig. 2, so that thespacing between the vise by the. blocks 17 and 18 is enough to permitthe work to be readily placed therebetween, it is only necessary for theoperator to then manipulate the valve 56 to instantly close the jawsupon the work. This valve may be of the push buttonvariety, asv hereindicated for simplicitys sake, ormay otherwise becontrolled eithermanually, or by the foot of the-operator, itbeing evident that: littleorno effort is required merely for the operation of the valve, and. it isnot necessary to laboriously pump up pressure for the operation of thevise. When thevalve 56 isopened. the air pressure thrusts the piston rod62! toward the. left, as viewed in Fig. l, and the fluid in thesystem:is. thus forced into. the space between the end surfaces 38 of: thecylinder 32and piston 35; The piston 35 is secured by the lock pin orscrew 50: to the sleeve 41 and hence, to. the vise body 10 so that thepiston cann0t, of course, move forwardly or rearwardly. There fore, thecylnider 32 must: of necessity be thrust rearwardly by. thefluidand-since the cylinder is.held by the anchor stud 28'to the visenut:24;the latter will be pulled in. a rearward direction so as. to.carry alongthe hand screw. 19. and movable vise jaw. 16, thusclosing-the jaws upon the work. Actually. thepiston.35' is braced atits: end against the shoulder formed bythe counterbore-49 but; the lockscrew. is providedtso that when the valve 56 is closed, andthe largecylinder section 58- vented to-atmosphere by. the valve, 21' return.spring 68' may assert itself and thrust the vise nut 24-.forwardlytoreopen the jaws. This return spring=68 isan expansion coil spring:braced between'the adjacentendj40 of the vise nut and a shoulder69'formed within the-cylindrical wall of the piston 35. The spring68'is, of course, compressedias the vise jaws are closed'by the fluidactuating means and, as stated, the spring acts to open the jaws whenthe fl'uid= pressure is relieved-in-the system. The keyway 45 and key 46provide for the necessary axial travel of the vise nut 24 whilepreventingthe nutfrom rotating in: the vise body-when the handscrew- 29is used for adjusting the spacing between the vise jaws.

The stroke. and bore of'the plunger 62and'sma-ll cylinder. section 59'are both so prop'ortioned' with reference to the stroke and bore of'thepiston 35 and cylinder 32 that fluid will not be supplied insuch-amount'as-might otherwise force the cylinder32*entirelyoif thepiston 35; should the vise behydraulically actuatedJwithout aworlc piecebetween the' v-ise jaws or=-the -vise be opened too far for the work.For example, the system is so .proporticmedthat the fluid displacedin.the'= small cylinder section' 59" will move the vise'ja'w'16one-half'inchonly. and this is sufiicient since it-ispossible-for the.operator to very easily make, a rough'adjustment within this rangelby.means of the handscrew. 19. Suchproportioning-of theisystem. alsois, ofcourse, selected so that the desired! pressure is brought to.bea-r,whiclndependsnotonlyt onthe size, of the vise andithe gripping pressuresnecessary, to the work but alsoupon the, available pressure; ofthecompressed air in theshop.

In Fig. 5I have.f.sho wn, my. invention as adaptedtO. the operationofJan ordinarymachine vise, ,suchasrused. upon a drill press or millingmachine to hold the work and which vise differs somewhat-from the.ordinary bench; vise. As here'shown' this machine vise comprises a base"70 at what may be referred to as the rear end of which there is astationary jaw 71. A movable jaw 72 is supported by a suitable keyway'(not shown) upon the base 70 for reciprocating movement toward and awayfrom the stationary jaw in the ordinary manner. The movable jaw isoperated by means of a hand screw 73 extending through a heavy boss orlug 74 cast upon the base 70 at the end thereof remote from thestationary jaw. The screw 73 is, of course, threaded into the movablejaw and in its opposite end is providedrwith a crank 75 by which thescrew may be rotated.

For the accommodation of my hydraulic operating means for this type ofvise the lug 74 is bored out at 76 coaxially with the screw 73, withsaid bore opening toward the vise jaws and closed at its opposite end 77except for an opening 78 to loosely clear the screw. This portion of thevise screw is provided with a smooth sleeve 79 which slides in theaforesaid opening 78, said sleeve being substantially longer than thelug 74 as measured axially of the screw., The recess formed by the bore76 nicely and slidably receives the cylinder 80 of the hydraulicmechanism, which cylinder has an annular wall or skirt as clearly shown,the end 81 of which engages against the end 77 of the lug. The oppositeend of the cylinder 80 is closed except for'an opening 82 through whichthe aforesaid sleeve 79 passes and bearing against this closed end ofthe cylinder is a collar 83 which is pinned to the hand screw 73, thediameter of which collar is substantially larger than that of theopening 82. Slidably arranged within the cylindrical wall of thecylinder 80 is a similarly shaped piston 84 the end 85 of which isbraced against the closed end 77 of the lug 74. Sliding fluid tightseals are provided between the piston and cylinder as well as betweenthe piston and the sleeve79 by inner and outer O-rings 86. Here again afitting 87 is used to convey fluid under pressure to the closed end ofthe cylinder 80,which has a tapped socket 88 to receive said fitting anda port 89 for leading the fluid to the interior of the cylinder betweenthe adjacent end surfaces 90 of cylinder and piston. The upper portionof the lug 74 is notched at 91 to clear the aforesaid fitting 87 and aflexible line 92 leads from the fitting to the source of operating fluidsuch as that disclosed in Fig. l. A second collar 93 is pinned to thescrew 73 some distance forwardly of the lug 74 and an expansion coilreturn spring 94 is braced between the end 77 of the lug and this secondcollar in order to normally bias the sliding parts forwardly or towardthe left, as viewed in the drawing.

In operation the movable jaw 72 is roughly adjusted to accommodate thework and upon the admission of fluid to the interior of the cylinder 80the cylinder will be thrust rearwardly or toward the right, as viewed inthe drawing, and by the engagement of the end of the cylinder with thecollar 83 will move the entire assembly of the movable jaw and screw 73in the direction of the stationary jaw in order to close the vise uponthe work. The action is thus essentially identical to that previouslydescribed and, of course, when the work is to be released and the fluidpressure holding the work is relieved the return spring 94 will act toreturn the jaw 72 to its starting or roughly adjusted position.

While the foregoing structure is arranged in and about the lug 74 of thevise I may also locate the operating mechanism within the body of themovable jaw itself as shown in Fig. 6. Here the base of the vise isdesignated at 70', the stationary jaw at 71, the movable jaw at 72',hand screw at 73 and the lug at 74. In this case, however, the screw 73is not threaded into the body of the movable jaw but the same isprovided with an elongated cylinder or bore 95 in which there isslidably mounted an operating piston, designated generally at 96. Thispiston is generally tubular in form having an annular wall 97 which isinternally formed to threadedly engage the screw 73. A portion 97a ofthe wall of the piston is enlarged to closely fit the bore 95 and thispart of the piston has a longitudinal keyway 98 in which there slidablyfits a key 99 secured within the bore 95 so that the piston may slidewithin the bore but cannot turn therein. At the end of the jaw nearestthe lug 74' there is an annular collar 100 which is screwed into thetapped end of the bore 95 to guide the piston and at the opposite endthe piston is closed, as indicated at 101, so that adjacent end surfaces102 are provided between the closed end of the piston and the closedextremity of the bore 95. A fluid tight sliding seal is provided betweenthe bore and the piston by means of an O-ring 103 and fluid may be ad-'amitted to the interiorof the bore for'coaction .with the surfaces 102through a port 104.communicating with-a laterally extending channel..105 which leads to afitti'ng and flexible line, such as that shown at87, 88 and 92in; Fig. 5. The structure is completed by theprovision ofan expansion coil return spring 106 which-is bracedbetween the aforesaidcollar and the enlarged part 97a of the piston wall.

The rotation of the hand screw 73 will, of-co'urse, here also roughlyposition the movable jaw 72' and the vise may then be hydraulicallyoperated and closed upon the work by the admission of the fluid totheclosed end of the bore 95. As the fluid enters through the port 104 themovable jaw is of necessity urged toward the stationary.

made in the structure as disclosed, provided such modifications comewithin the spirit'and scope of the appended claims. Having now thereforefully illustrated and described my invention, what I claim to be. newand desire to protect by Letters Patent is: H

l. A combination manually and hydraulically actuated work holding vise,comprising a body having astatlonary aw, a movable jaw having apartslidable in said body for moving that jaw toward and away from thestationary aw, a hand screw and a nut threaded thereon in said body formanually positioning the movable jaw toa ward and away from thestationary jaw, a cylinder anchored to said nut, meansfor supplyingfluid under pressure to one end of the cylinder,'and a piston inside thecylinder and over which piston the cylinder is slidable, the cylinderbeing operative upon admission of said fluid thereinto and the thrust ofsaid fluid against the piston to thereby draw the screw and nutlengthwise and force the movable jaw toward the stationary jaw.

2. A combination manually and hydraulically actuated work holding vise,comprising a body having a stationary aw, a movable jaw having a partslidable in said body for moving that jaw toward and away from thestationary aw, a hand screw and a nut threaded thereon in said body formanually positioning the movable jaw toward and away from the stationaryjaw, a cylinder anchored to said nut, means for supplying fluid underpressure to one end of the cylinder, a piston secured to the vise body,said cylinder being slidable over the piston, and the cylinder beingoperative upon admission of fluid thereinto to draw the movable jawtoward the stationary jaw, and a spring operative to normally urge thejaws apart.

3. A vise comprising a hollow elongated body and a stationary aw at oneend thereof, a cooperative movable aw having a slide reciprocablymounted in the body, an elongated tubular vise nut slidably andnon-rotatably located in said slide and a hand screw threaded thereinfor rough positioning of the movable jaw with reference to thestationary aw, an anchor member secured to the nut and extending fromthe end of the vise body opposite the aws, a hollow vise actuatingcylinder secured by one end to the anchor member, a hollow piston insidethe cylinder and over which piston the cylinder is slidable, the anchormember extending slidably through the piston, means securing the pistonto the vice body, and means for supplying fluid under pressure to thecylinder to move the cylinder and plston relative to each other andthereby urge the movable jaw toward the stationary jaw in any positionof the latter as adjusted by the hand screw.

4 A v1s e comprising a hollow elongated body and a stationary aw at oneend thereof, a cooperating movable aw having a slide reciprocablymounted in the body, an elongated tubular vise nut slidably andnon-rotatably located in sa1 l slic ie and a hand screw threaded thereinfor rough posltloning of the movable jaw with reference to thestationary jaw, an anchor member secured to the nut and extendlng fromthe end of the vise body opposite the aws, a hollow vise actuatingcylinder secured by one end to the anchor member, a hollow piston insidethe 5. A vise comprising ahollow elongated bodyand astationary jaw atone endlthereof, a cooperating movable jaw having at slidereciprocabl y'mounted in the. body, an. elongated tubular vise nut slidably andnonrotatabiy. located in said slide and a hand screw threaded thereinfor rough: positioning of the: movable jaw withreference to: the.stationary jaw, an anchor stud screwed into the vise nut1andprojectingaxially therefrom, an end extension sleeve secured tothe rear end" ofthe vise body, a hollow piston slidably receiving said anchor stud andbraced against said end sleeve, a cylinder surrounding the piston and:secured rearwardl'ythereof to said: anchor stud; both the pistonand"cylinder having end' faces, andmeansfor supplying fluid to thecylinderbetween said end faces totthrust the'cylinder'rearwardly and therebydrawthe visenut rearwardly and close the movable jaw toward: the.stationary jaw.

6. A- vise comprising a hollow elongated body and astationary jaw atoneend thereof, a cooperating-mow" able jaw having a. slidereciprocably'mounted-in the body, an elongated tubular vise nut slidablyand non-rotatably located in; said slide and: a hand screw'threadedtherein for rough" positioning of the movable jaw with reference to thestationary jaw, an: anchor stud screwed into the vise. nut andprojecting axially therefrom, an end extension sleeve. secured to therear end of the vise body, ahollow piston slidably receiving'saidlanchor stud and braced against said: end sleeve, a cylinder surroundingthe piston and seoured rearwardly thereof to said anchor: stud, boththe: piston and-cylinder having end faces, meansfor supplying" fluid tothe cylinder between said'end faces to-thrusb the cylinder rearwardl'yand there-- by draw the vise nut rearwardly and close the movable jawtoward the stationary jaw, meanssecuring the pis-' ton: to the end plug,and a spring braced between the piston and the vise nut to normally urgethe movable jaw forwardly.

7. A vise comprising a hollow elongated body and a stationary jaw at oneend thereof, a cooperating movable jaw having a slidereciprocablymounted in the body, an elongated tubular vise nut slidably andnon-rotatablylocated in said slide and ahand screw threaded therein forrough positioning of-the movable jaw with reference to the stationaryjaw, an anchor stud screwed into the vise nut and projecting: axiallytherefrom, an end extensionsleeve secured to the-rear end of the visebody, a

hollow piston slidably: receiving said anchor stud and braced againstsaidend sl'eeve, a cylindersurroundi'ng the piston and securedrearwardly. thereof 'to'said anchor stud, both the piston and. cylinder.having end faces, meansfor supplying fluid to the cylinder between: saidend faces to' thrust the cylinder rearwardly and thereby draw the visenut rearwardly andclose the movable jaw toward the stationary jaw, andsaid vise nut and-end sleeve having a cooperating key and keyway to lockthe nut against rotation but permit forwardand rearward movementthereof:

Refere'nces-Gited in the file of this patent UNITED STATES PATENTSNumber Name Date 2,222,941; Freeman Nov. 26, 1940 2,258,466 'Naylor Oct.7, 1941 2,402,411 Kent June 18, 1946 2,444,304 Miller- June 29, 1948FOREIGN PATENTS Number Country Date 332,372 Germany Jan. 31, 1921

